Predicting climate change’s effects on birds

The National Audubon Society’s annual Christmas bird count is in full swing as volunteers fan out across the country counting birds and species. Researchers are currently using the counts to help predict how climate change will affect bird populations, according to the Audubon Society, which says climate change and urban development are now the greatest threats to birds.

Similar changes in bird behavior could be seen this year in the Midwest and parts of the South, areas that have been gripped by a massive drought that covered two-thirds of the nation at its height. The drought’s severity is unusual, but scientists warn that such weather could become more common with global warming. Birds — as well as other animals — will have to adapt, and the data collected in the Christmas count gives crucial insight on how they might do that. The dataset is notable for its size and the decades that it covers. Along with showing how birds adapt to climate change, it reveals the impact of environmental changes, such as habitat loss, which has contributed to a 40 percent decline in bird numbers during the past 40 years, said Gary Langham, vice president and chief scientist for the National Audubon Society. “We’ve converted the landscape dramatically, and then you add climate change to the mix … and the results are more alarming,” Langham said.

Scientists have used the data to predict bird populations and behavior in 2020, 2050 and 2080. They also could use it to advance conservation work or calls for emergency action, he said. Birds, though, are only one part of an ecosystem. As they move from place to place, they encounter new predators and species that may be competing for the same food. Vegetation also is changing as the Earth warms and some areas become more drought-prone. What happens as all these changes take place? “It’s the million dollar question. When you have that kind of ecological disruption, no one knows what happens,” Langham said. “There are going to be winners and losers. There will be some that become more common, and some that will go extinct.”

…Birds are early indicators of environmental problems. “This is not just about counting birds,” says Gary Langham, Audubon’s chief scientist. “Data from the Audubon Christmas Bird Count are at the heart of hundreds peer-reviewed scientific studies and inform decisions by the U.S. Fish and Wildlife Service, the Department of the Interior, and the EPA. Because birds are early indicators of environmental threats to habitats we share, this is a vital survey of North America and, increasingly, the Western Hemisphere.”

The longest running wildlife survey in the world, Audubon’s annual Christmas Bird Count (CBC) has continued through World Wars I and II and The Great Depression. The holiday tradition began when ornithologist Frank Chapman proposed that people “hunt” birds only to count them. Dr. Chapman’s initiative came during a time when birds were being slaughtered for fashionable hats. Now the greatest threats to birds include sprawl, development, loss of wetlands and climate change.